平板式与真空管式太阳热水器热性能分析比较

在太阳热水器中依据吸热体的形状,可将其分为平板式太阳热水器和真空管式太阳热水器两大类。由于吸热体形状的不同,导致这两类热水器在热性能上各有差异。在家用太阳热水器热性能测试的国标中,热性能指标主要有日平均效率η d、平均热损系数 UL和非稳态效率方程。其中,日平均效率η d描述了在正常天气状况 (晴天 )下,一日内在热水器采光面上接收到的太阳辐射量中转化为提高水箱水温的热量的百分比;平均热损系数则反映了在无日照等条件下,热水器整体的保温性能;而非稳态效率是上述的热转换效率在不同时点的体现,非稳态效率方程则是…     

家用太阳热水器热性能试验方法探讨

一前言国家推荐标准ＧＢ／Ｔ１２９１５ ９１“家用太阳热水器热性能试验方法”中采用平均日效率的概念来反映太阳热水器获取能量的性能。平均日效率高的热水器意味着其平均热性能较好 ;反之 ,热性能较差。用户和质量检测部门也以此作为反映热水器质量的主要依据。但我们在长期的测试工作中发现 ,该标准有以下几方面问题值得商榷。１ 日平均热效率从用户要求和研究角度两个方面仔细考虑 ,发现用户使用太阳热水器 ,主要关心在不同气象情况下 ,每天能提供热水的温度和水量 ,以及每天不同时间水箱中的水温。而从研究角度 ,关心的是热水器在不同…     

平板式与真空管式太阳热水器热性能分析比较

在太阳热水器中依据吸热体的形状 ,可将其分为平板式太阳热水器和真空管式太阳热水器两大类。由于吸热体形状的不同 ,导致这两类热水器在热性能上各有差异。在家用太阳热水器热性能测试的国标中 ,热性能指标主要有日平均效率 ηｄ(ηｄ =Ｍｃｐ(ｔｅ -ｔ0 ) / (ＡＨ)、热损系数Ｕｌ(Ｕｌ =Ｍｃｐ(ｔ1-ｔ4 ) / [Ａ(ｔｍ -ｔａ)Δτ) ]和非稳态效率方程。其中 ,日平均效率 ηｄ 描述了在正常天气状况 (晴天 )下 ,一日内在热水器采光面上接收到的太阳辐射量中转化为提高水箱水温的热量的百分比 ;平均热损系数则反映了在无日照等条件下 ,热水器…     

闷晒太阳热水器及其制作

在形式多样,种类繁多的太阳热水器中,有一种简单易作而又很实用的热水器——闷晒太阳热水器。这种热水器由透明盖板、集热水箱、保温层和外壳构成,它省去了循环式热水器中连接集热板和水箱的管道,减少了热损。由于闷晒太阳热水器的集热器与水箱合为一体,所以国外也有人把这种热水器称为“紧凑型热水器”。闷晒太阳热水器成本较低,占地较少,且易于安装,在不少国家得到了广泛的应用。我国有些地方,如上海、河北、辽宁、北京等地也先后研制成了多     

新型贮热水箱的热性能研究

对太阳热水器贮热水箱的结构进行改进,并从平均日效率和平均热损系数两个方面对太阳热水器进行实验研究。结果表明:与常规系统相比,采用新型贮热水箱的太阳热水系统平均热损系数下降1.35~3.42 W/(m2·K),平均日效率提高2.37%~4.02%。     

浅谈家用太阳热水器热性能测试

如何评价与检测家用太阳热水器的热性能呢？国家质量监督检验检疫总局于2002年4月28日发布了国标GB／T 18708—2002《家用太阳热水系统热性能试验方法》，通过此试验方法可得到太阳热水器能量输入一输出曲线图，它全面系统地反映了在不同的季节、不同的太阳辐照量条件下的太阳热水器能量输入一输出特性，实现了我国太阳热水器产品的热性能试验与国际接轨。     

怎样提高真空管式太阳热水器日平均热效率

衡量太阳热水器热性能的重要指标之一是日平均热效率，日平均热效率越高，相同条件下整机有效得热量就越大。我们知道平板式太阳热水器日平均热效率大都在60％以上，而全玻璃真空管太阳热水器日平均热效率只有45％（国标）左右，问题出在哪里呢？     

一种新型热水器

目前国内市场的热水器,不外两大类:即燃气式和电热式。由于我国近期燃气不能普及,二次能源的电力也不能充分供给,故这两类热水器的市场覆盖面均受到能源条件的限制。“多能源蓄热式热水器”是考虑我国当前民用燃料供给条件所设计,该热水器具有节能和适用不同种类燃料的特点,热水器由水箱燃烧系统、控制系统和传送管路所组成,水箱用于加温和贮存热水,厂家可在水箱内装设电热器,燃气燃烧器或螺旋管式热交换器。     

闷晒式全玻璃真空管太阳能热水器

太阳能热水器主要由集热器与水箱两部分组成。集热器把太阳能转变为热能,靠自然对流或强迫对流把热能储存在水箱中,并有效地防止热损失。评价太阳能热水器性能的好坏,主要看集热器吸热量的多少和水箱散热损失的多少。集热器的吸热量越多,水箱的散热损失越少,其性能越好。不管是平板型的太阳能热水器,还是真空管     

日平均效率是太阳热水器重要的热性能指标

随着我国太阳能事业的发展 ,真空管式太阳热水器已经逐渐替代了平板式 (管板式 )太阳热水器而成为太阳热水器的主导产品 ,由于两类热水器的结构有着较大的不同 ,因而在某些热性能上将会出现较大的差异 ,如平板式太阳热水器的非稳态效率曲线是一条斜率为负值的直线 ;而真空管式太阳热水器的非稳态斜率曲线则是一条凹形曲线。再如 ,两类热水器的热损系数计算公式也应因各自散热主体的不同而有所差别 (此部分将另文讨论 )。因此 ,在制定新的太阳热水器热性能试验的国标时 ,应全面考虑这些不同和差异 ,以求得制定出更科学合理的国标。与此同时 ,…     

真空玻璃盖板热管平板式太阳能热水器的研制

介绍了研究成功的采用真空玻璃盖板的热管平板式太阳能热水器,测试了其性能,并与全玻璃真空管太阳能热水器和蜂窝热管太阳能热水器进行了比较。实测得到,真空玻璃盖板热管平板式热水器的日平均效率比后两分别大13．3％和6．5％,平均热损系数比后两分别小52．5％和21．5％。真空玻璃盖板平板式太阳能热水器性能优越,有很好的应用前景。     

Correlation of solar water heater test data

A method of correlating outdoor solar water heater test data, so that long-term average system performance can be evaluated from short-term testing is presented. The test procedure is based on monitoring the outdoor operation of a solar water heater until a range of test conditions are experienced. The procedure is shown to give reliable results for a range of cold water and thermostat set temperatures. The correlation procedure also gives consistent predictions of system performance from test data collected at test sites ranging from tropical to cold temperate climate types.     

真空管太阳能热水器冬季热性能研究

本文根据GB／T19141—2003,设计建立了一套太阳能热水器热性能的测试系统,并用此系统对天津市场上销售的16种太阳能热水器产品进行了冬季的热性能测试,并分析了其主要的热性能指标,日有用得热量和平均热损因数。     

Theoretical and experimental investigations of a two-phase thermosyphon solar water heater

This article experimentally and theoretically investigates a two-phase thermosyphon solar water heater. The performance of this innovative solar water heater at different solar radiation intensities and tilt angles are experimentally discussed. The results show the best charge efficiency of the system is 82%, which is higher than the conventional solar water heaters. The theoretical model is also developed using the thermal resistance-capacitor method. The simulation predictions agree well with the experimental data within an average error deviation of ±6%. Two methods for improving the performance of this heater, double fin tubes and nano particle, are proposed. The results show that charge efficiencies can increase 3% and 4%, respectively, according to the theoretical model.     

住宅太阳热水器的技术经济性分析

以福州地区典型气象年逐时气象数据为基础,对平板型太阳热水器的热性能进行逐时模拟。利用综合能源价格法,分析集热器面积对太阳热水器经济性的影响,并比较各类热水器的技术经济性。在当前能源价格体系下,集热器面积为8.5m~2时,系统的年平均太阳能保证率最大(为67.72%);集热器面积为4m~2时,综合能源价格现值最小(为0.283$/kWh),此时系统的年平均太阳能保证率为62.65%。     

Experimental investigation on thermal performance of thermosyphon flat-plate solar water heater with a mantle heat exchanger

The thermal performance of thermosyphon flat-plate solar water heater with a mantle heat exchanger was investigated to show its applicability in China. The effect on the performance of the collector of using a heat exchanger between the collector and the tank was analyzed. A “heat exchanger penalty factor” for the system was determined and energy balance equation in the system was presented. Outdoor tests of thermal performance of the thermosyphon flat-plate solar water heater with a mantle heat exchanger were taken in Kunming, China. Experimental results show that mean daily efficiency of the thermosyphon flat plate solar water heater with a mantle heat exchanger with 10 mm gap can reach up to 50%, which is lower than that of a thermosyphon flat-plate solar water heater without heat exchanger, but higher than that of a all-glass evacuated tubular solar water heater.     

全玻璃真空管太阳能空气集热器热性能试验方法研究

全玻璃真空管空气集热器是一种热损较小的太阳能空气加热装置,该文对该类集热器热评价方法进行了研究,并对集热器的时间常数,热延迟常数,角系数修正因子及瞬时热效率的实验方法进行了初步的实验研究,研究表明,用热延迟常数比时间常数能更好地反映真空管集热器的性性能,真空管集热器的角系修正因子在垂直入射时最小。     

Long-term thermal performance of a two-phase thermosyphon solar water heater

This article investigates experimentally the long-term thermal performance of a two-phase thermosyphon solar water heater and compares the results with the conventional systems. Experimental investigations are conducted to obtain the system thermal efficiencies from the hourly, daily and long-term performance tests. Different heat transfer mechanisms, including natural convection, geyser boiling, nucleate boiling and film-wise condensation, are observed in the two-phase thermosyphon solar water heater while solar radiation varies. The thermal performance of the proposed system is compared with that of four conventional solar water heaters. Results show that the proposed system achieves system characteristic efficiency 18% higher than that of the conventional systems by reducing heat loss for the two-phase thermosyphon solar water heater.     

Study of a solar water heater using stationary V-trough collector

There are various types of solar water heater system available in the commercial market to fulfill different customers’ demand, such as flat plate collector, concentrating collector, evacuated tube collector and integrated collector storage. A cost effective cum easy fabricated V-trough solar water heater system using forced circulation system is proposed. Integrating the solar absorber with the easily fabricated V-trough reflector can improve the performance of solar water heater system. In this paper, optical analysis, experimental study and cost analysis of the stationary V-trough solar water heater system are presented in details. The experimental result has shown very promising results in both optical efficiency of V-trough reflector and the overall thermal performance of the solar water heater.     

Performance prediction of two models of solar water heaters using a thermal trap

The performance of a built-in storage type of water heater can be improved using the principle of the thermal trap. In the following article, we have proposed two designs of solar water heater with a thermal trap and studied their performance for different duty cycles. A comparison is made with a water heater without a thermal trap. We have found that the proposed designs are nearly as good as the heater without a thermal trap but having a night insulating cover to decrease energy loss for the no-sunshine period.